The work in progress seeks to clarify the role of thyroid hormone on maturational processes involving central (neuronal) and peripheral (non-neuronal) structures in the emergence of coordinated behavior. The development of coordinated activity between hand and mouth will be the model for our studies, since the relationship between the two anatomical entities is established very early in ontogeny and is incorporated perinatally and postnatally in the well known palmomental and Babkin reflexes. Developmental correlations, both intracentrally and between neuronal and non-neuronal structures which are instrumental in the elaboration of this relationship will be evaluated under: (a) normal, and (b) induced hypothyroid states in pregnant animals such that maternal and fetal thyroids are inhibited. The quantitative and qualitative aspects and the temporal sequence of this behavior pattern under normal and experimental conditions are currently under way.